Resampling ECG signal from Physionet 2017 datset

I am trying to resample the ECG Signal from the file in the link. It is an array of dimension 5969x18000 wherein each ECG waveform is stored in a row.

Link for ECG File: https://drive.google.com/file/d/1vXb3zY1hlKdXbn6cSvrm7O7OfL1Nx_qe/view?usp=share_link

ecg = load('train.mat');
ecg_signal = ecg.array(3,:);
fs_original = 300; % original sampling frequency in Hz

% Define the new sampling frequency
fs_new = 100; % new sampling frequency in Hz

% Re-sample the signal using the resample function
ecg_resampled = resample(ecg_signal,fs_new,fs_original);

% Plot the resampled data
figure;
plot(ecg_resampled);
title('Resampled ECG Data (100 Hz)');

But the result I am getting is still not satisfactory. I need to implement some QRS detection algorithm so I am trying to resample it so that the algorithm gives more accuracy.

I was expecting results similar to below picture:

Could someone suggest me how to do it?