# CathSource vs STS Cardiothoracic Surgery

The clearest difference is rating: STS Cardiothoracic Surgery at 4.8 against CathSource's 1.6. STS Cardiothoracic Surgery also leads on monetization model (free with in-app purchases vs paid) and ratings volume (205 vs 24). On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

STS Cardiothoracic Surgery holds the better App Store score, 4.8 against 1.6. That said, the two scores are not equally well evidenced: STS Cardiothoracic Surgery has 205 ratings behind it against 24, so its average is the more settled of the two. Written reviews point the same way: 40% of CathSource's written reviews are positive against 50% of STS Cardiothoracic Surgery's.

CathSource ships an update every 2 months, STS Cardiothoracic Surgery every 4 months. The most recent releases landed on October 29, 2026 and October 22, 2026 respectively.

## The numbers

| Metric | CathSource | STS Cardiothoracic Surgery |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [1.6 (24 ratings)](https://appshunter.io/ios/app/cathsource/id420847275/reviews) | **[4.8 (205 ratings)](https://appshunter.io/ios/app/sts-cardiothoracic-surgery/id1530044637/reviews)** |
| Number of ratings | 24 | **205** |
| Positive reviews | 40.0% of reviews | **50.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 4 months |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 79 MB | 14 MB |
| Requires iOS | 18.5 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod, Mac** |
| Age rating | 12+ | 17+ |
| Developer | [ECGsource LLC](https://appshunter.io/developer/377139096) | [Unbound Medicine, Inc.](https://appshunter.io/developer/300420400) |

## What reviewers say

### CathSource

[App page](https://appshunter.io/ios/app/cathsource/id420847275)

A comprehensive medical reference focused on cardiac catheterization and angiography. It offers a searchable index of specialized topics, a database of videos of common and rare findings, and a collection of images including hemodynamic formulas and tables.

**Highlights:** Searchable index of cardiac catheterization topics, Database of coronary angiogram, ventriculogram, and aortogram videos, Image database with hemodynamic formulas and tables, Covers common and rare cardiovascular pathologies, Developed by practicing Interventional Cardiologists

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### STS Cardiothoracic Surgery

[App page](https://appshunter.io/ios/app/sts-cardiothoracic-surgery/id1530044637)

This app is a comprehensive digital resource for cardiothoracic surgical information, offering updated content in cardiac and thoracic surgery. It features extensive multimedia, including illustrations, photographs, and surgical videos, for educational and reference purposes.

**Highlights:** Continuously updated surgical information, Multimedia content: illustrations, photos, videos, Covers general thoracic and cardiac surgery, Accessible on mobile devices 24/7, Interactive chapters, Based on leading textbooks and surgeon expertise

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is CathSource free?

CathSource is free to download, with no in-app purchases.

### Is STS Cardiothoracic Surgery free?

STS Cardiothoracic Surgery is free to download, with no in-app purchases.

### Which has better reviews, CathSource or STS Cardiothoracic Surgery?

STS Cardiothoracic Surgery is rated higher. CathSource averages 1.6 out of 5 from 24 ratings, while STS Cardiothoracic Surgery averages 4.8 from 205 ratings.

### Do CathSource or STS Cardiothoracic Surgery have ads?

Neither CathSource nor STS Cardiothoracic Surgery shows ads.

### Which is updated more often, CathSource or STS Cardiothoracic Surgery?

CathSource ships an update every 2 months, and STS Cardiothoracic Surgery every 4 months. Most recently, CathSource was updated on October 29, 2026 and STS Cardiothoracic Surgery on October 22, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*